This invention relates to Hall sensor devices which can suitably be utilized, for example, for the detection of the crankshaft angle of an internal combustion engine for controlling the ignition timing. This invention relates also to a method of producing such devices.
Various Hall sensor devices utilizing the Hall effect for converting the variations of magnetic flux into an electrical signal are well known; they include, for example, position sensors, angle sensors, and velocity sensors. In particular, Hall sensor devices are utilized for detecting the crankshaft angle of an automotive engine in the contactless type ignition system. Further, Hall IC's (ingegrated circuits) which incorporate a Hall element in a hybrid integrated circuit are also well known. Furthermore, Hall sensor devices in which such a Hall IC is accomodated integrally with a magnetic circuit in a resinous casing or frame are also known.
However, the last-mentioned integrally molded Hall sensor devices still have the following disadvantges. Namely, during the molding process of the casing or frame, the constitutive parts of the Hall sensor device, such as the Hall IC or the magnetic circuit parts, should be precisely positioned and fixed within a mold, utilizing a number of jigs for the respective parts; thermoplastic or thermosetting resin is poured into the mold while the parts are thus kept in their respective positions, to be dried or set in a heating furnace, thereby forming the casing or the frame. Thus, the process is in need of a multitude of jigs for folding the parts at their respective positions during the molding step, and the accuracy of the positioning of the parts is low; as a result the process is not suitable for automated mass production; in addition, the Hall sensor devices produced by this process have low signal precision.